Building Telephony Systems with OpenSER is a new book from Packt, which acts as a step-by-step guide to building a high performance Telephony System. Written by Flavio E. Goncalves, this book teaches users how to develop a fast and flexible SIP server using OpenSER, an open-source VoIP server based on the Session Initiation Protocol (SIP), an application-layer control (or signaling) protocol for creating, modifying, and terminating sessions with one or more participants, including internet telephone calls, multimedia distribution, and multimedia conferences. This book is a well illustrated, step-by-step guide to building a SIP based network using OpenSER.